scbjbner



(No Model.) 2 sheets-Sheet 1.

4C. E. SCRIB'NER.

DOUBLE SPRING LOOP KEY AND OIROUIT POE MULTIPLE SWITCH BOARDS.

, Pa/Ltented Deo. 27, 1887.

@2x3/ZE@ f L (No Model.) 2 sheets-sheec 2.

C. E. SCRIBNER.

"DOUBLE SPRING LOOP KEY AND CIRCUIT POR MULTIPLE SWITGIIBOARDS. No. ,685. P --.D 18 375 a l Stammeo H27 mill fz rrycy,

UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VESTERN ELECTRIC COMPANY, OE SAME PLACE.

DOUBLE-SPRING LOOP KEY AND CIRCUIT FOR MULTIPLE SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent NO. 375,685, dated December 27, 1887.

Application filed May 12, 1885. Serial No. 165,276. (No model.)

To @ZZ 1071/0772, it may concern.-

Be it known that I, GHAELEs E. SCEIENER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illi nois, have invented a certain new and useful Improvementn DoubleSpring Loop Keys and Circuits for Multiple Switch-Boards, of which the followingis a full, clear, concise, and exact description, reference being had tothe accompanying drawings, forming apart of this specification.

The object of my invention is to enable the switchman to switch his telephone into the circuit of any single telephone-line or to loop his telephone into the pair of cords connecting two subscribers7 lines. In the former case a ground must be provided for the single line at the central oiiice, and in the latter case, when the telephone is looped into a pair of cords, the central-office ground must be cut off. I accomplish all this work by means of the single loop-switch and the circuits which I will now describe.

In the drawings, which are illustrative of my invention, Figure l is a sectional view of my switch, a portion of a telephone switch-board, and the circuitconnections at the central ofiice. Fig. 2 is a diagram View showing the circuits between three similar switches. Fig. 3 shows one of the positions of the switch.

Like parts are indicated by similar letters of vreference in the different figures.

As shown in Fig. l, the loop-switch consists of the three insulated springs a, b, and c, mounted upon the block d, of insulating material, the plunger e, operated by the cam-lever f, and the insulated contact-points g, h, and z', against which, respectively, the insulated springs normally rest. The spring a is provided with the piece of insulating material k. The plunger e is shown held up against the metallic piece Z. When the cam-lever is lifted to its upright position, the plunger is forced down out of contact with the said metallic connecting-piece Z, and the beveled end of the plunger being forced against the insulated end 7c of spring a, said spring will be lifted from point g without coming in contact with or changing the position of spring b. This middle position of the plunger is illustrated by switch 3 at the right in Fig. 2. If, however, the cam-lever isca-rried over to the right, the spring a will return to its first po sition in contact with point g,while the springs Z) and c will be lifted from their contact-points h and t', respectively, as shown in Fig. 3. There are, then, three positions assumed by the plunger-inst, as shown in Fig. l; second, as shown by switch 3 of Fig. 2, and, third, as shown in Fig. S-and the circuit-connections 6o are different in each of the different positions.

. I will now describe the operation of my device. As shown in Fig. I, the operators telephone 'm is included in the circuit ofthe telephonelinewithwhich the corda is connected. This circuit may be traced as follows: beginning at cord n, thence to spring b and point h, thence by wire o through telephone m, thence to contact-point t', thence to spring c, thence through the clearing-out annunciator to socket 7o q, thence to the plunger e, thence to metallic piece Z, from metallic piece Z to contact-point g, and thence to spring d, thence by wire 1', through the retardationcoil s and battery t, to ground, as shown.

The point of plug a is shown touching the frame ofthe switchA of a telephoneline for the purpose of testing to nd out whether the line of the switch is in use or connected at some other multiple switch-board. t 8o The springjacks and telephone may be connected and provided with test-circuits, as shown in my Patent No. 305,021, of September 9,1884. Itherefore deem it unnecessary tofully illustrate the spring-jacks and telephone-line circuits connected therewith. If the line wanted is in use, the battery t will find circuit through the telephone m and plug a to line, and the usual click will be heard in the telephone when the test is made, as shown in Fig. 9o l. Ifthe line is free, there will be no circuit found to line and no click in the telephone,

and the switchman will insert the plug into `the springj ack and then throw the cam-lever 'said series.

cords. By bringing the cam-lever to the upright position, as shown in switch 3, Fig. 2, the telephone may be looped into the circuit of the cords connecting the two lines, while the ground-connection will be broken at point g. The operator may thus listen out.

My switch and circuits maybe used in counection with the ordinary standard switchboard system, in which no test is required to determine whether a line wanted is in use.

The platesZ of the loop-switches ata switchboard are connected together and also to point g of the first ofthe series, as shown in Fig. 2. The points h of the series of switches 1, 2, and 3 are all connected to o ne side of the telephone m. The poiutsZ of said series are allconnected with the other side of the telephone. The wire i) connects together thc metallic pieces Z of Metallic plate Z of switch 1 is connected by wire w to point g of said switch. Spring a of switch lis connected to point gof switch 2, and spring a of switch 2 is connected withpoint gof switch 3, and spring a of the last switch-switch 3is connected with the groundwire r. If, therefore, the spring a of any switch is lifted fromits opposing point y, it is evident that the ground-wire r will be cut off from alll the plates Z, and hence from the telephone; and it is evident that this is necessary in order that the operator may listen out. At all other times the telephone remains connected with the ground-wire r. The cam-lever remains upright, as shown in switch 3, only during the act of listening out.

If the conversation between the subscribers has ceased-,the operator will immediately throw the lever to the left, bringing the switch to its ordinary or normal position, as shown in switches 1 and 2. If the conversation is found to be still going on, the operator will throw the eam-lever to the right, as shown in Fig. 3. It is, therefore, as before stated, only during the act of listening out that the telephone is cut off from the ground-wire 1^.

It will thus be seen that the telephone is -normally in the circuit of all the idle cords n of the series, so that either of said idle cords may be used at once for making the connection with the spring-jack of a subscriber who has sent in a call without moving the camlever, as has been necessary heretofore. Many motions ofthe camlever are thus avoided and much time and labor saved.

1. The telephone of the operator, in combination with ground-wire r, the intermediate switching device operated by a cam-lever, and the pair of cords and said cam-lever, whereby the circuit ofthe telephone is closed to groundwire r when the cam-lever is in either of two of its positions, said connection being broken when the camlever is brought to its third position to loop the telephone into the circuit of said pair of cords.

2. The series of switches, each provided with the metallic connecting plates Z, said metallic pieces being connected together, the telephone m, connected with points h 'i of each of the switches, the ground-connection r, connected with spring a of the last switch, point g of the last switch being connected with spring a of the next, and point g. of the first switch being connected to plate Z thereof, and the plungers and cam-levers of the switches, whereby the ground connection is cut offfrom the telephone when the telephone is looped into the pair of cords of any switch.

3. The switch consisting of the insulated springs a b c, mounted on the block d, the plunger e, and camleverf, for moving the plunger to either of the three positions, the contactpoints g h ,and circuits, substantially as shown and described.

4. The switches provided with contaetpoints h Z, including a telephone, a pair of cords with each switch, and cam-lever mechanism for opening the circuit at the telephone contaetpoints of each switch when the cords of the vswitch are in use, whereby any c ord a of an idle pair of cords may be used for making connection with the telephone-line ofa subscriber without changing the position of the switch of said idle pair of cords.

5. The combination, with the ground-wire including the battery and retardation-coil, of the spring of the switch to which said wire is connected, the telephone connected with the telephone'contaets of said switch, the pair of cords with terminal plugs, and the spring jack switches and connections, whereby when one cord is connected to a subscribers switch the other cord may be used for testing,as described.

6. The combination, with the telephone switch board spring jacks, of a series of switches, 1 2 3, &c., each of said switches consisting of three insulated springs, three insulated contact-points, metallic plate Z, a plunger, and a cam-lever for operating the plunger, and circuits connecting said switches with the ground and with the operators telephone, and a pair of connecting cords and plugs with each switch, substantially as shown and described.

7. The combination, with a multiple switchboard aud the spring-jack switches placed thereon, of the operators telephone, a ground` circuit including a battery with a retardation coil, and intermediate switching mechanism, whereby the telephone may be looped into a circuit between any two spring-jacks and the ground cut-oft by a single movement of the switching mechanism, and whereby connection may be made from any spring-jack through the telephone to the ground-circuit, substantially as and for the purpose specified.

In witness whereof I hereunto subscribe my name this 28th day of April, A. D. 1885.

CHARLES E. SCR-IBNER.

Vitnesses:

F. H. McCULLoon, GEORGE P. BARTON.

ICO

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